Recipients of bank checks deposit the checks in the recipients'bank accounts. The depositary banks then transmit the deposited checks to a central clearing station, which in the United States managed by a division of the federal government.
FIG. 1 illustrates a stack 3 of paper bank checks which represents checks collected at the clearing station. One check 6 is shown in detail. The clearing station undertakes a check-clearing process, wherein accounting is done to settle accounts among the banks involved. The clearing house then distributes the checks to the banks on which they were drawn.
Recently, with the advent of inexpensive, high-speed digital computation, and because of various governmental regulations, a movement has originated to eliminate the distribution of the paper bank checks. Instead, optical scanners are used to generate digitized images of the checks, and the digitized images are then distributed electronically to the drawee-banks. The paper checks 3 in FIG. 1 are then held in long-term storage, in case they are needed.
FIGS. 2-5 illustrate conceptually the digitizing process. Each check 6 is divided into pixels 9, as in FIG. 2. FIG. 2 is a simplification: the number of pixels actually used is much larger than that indicated by the Figure.
Each pixel is assigned a value, or number, which indicates optical properties of the pixel. For example, if grey-scale photography is used, then the number indicates the relative greyness of the pixel, on a scale ranging from pure white to pure black. FIG. 3 provides an illustration, and shows three pixels 9. If a pixel is pure black, and if one byte is associated with each pixel, then the pixel is assigned the number 255. If a pixel is pure white, it is assigned the number zero. If a pixel is grey, it is assigned a number between 1 and 254, depending on the degree of greyness.
The numbers for the pixels are arranged in a convenient sequence, such as that suggested by FIG. 4. The top row of pixels is assigned positions 1 through 37 in the sequence. The second row is assigned positions 38 through 74, and so on.
Thus, each bank check is, in effect, converted to a sequence of numbers, such as the sequence shown in FIG. 5, wherein B(1) refers to the first byte in the sequence, and represents the grey-scale value of pixel number 1 in FIG. 4. Byte B(2) in FIG. 5 represents the value of pixel number 2 in FIG. 4, and so on. The sequence is shown as terminating in B(10,000) because ten thousand is considered a good estimate of the total number of pixels currently used to digitize a bank check.
The sequence of numbers of FIG. 5 will be termed the “image-data” of the check.
Once the image-data is generated, copies of the original check can be produced from the image-data. The copies can be displayed on a computer screen, printed on paper, or both, using known methods.
However, in order to produce accurate copies, certain technical information must be known about the original image-data. For example, the actual size of each pixel 9 in FIG. 2 must be known, to create a copy of the same size as the original.
As a second example, the length and width of the image, in pixels or equivalent, must be known. As a third example, it must be known whether the pixels represent color-values (not discussed herein), grey scales, or other representations. As a fourth example, it must be known whether the image-data is compressed and, if so, what compression algorithm was used.
This technical information, and other technical information, is generally attached to the image-data. Various file formats have been developed which package the two groups of data together, namely, (1) the image-data and (2) the technical information.
One file format which has achieved widespread usage is the Tagged Image File Format, or TIFF. A specification which defines the TIFF format is available from Adobe Systems, San Jose, Calif., USA.
Some banking systems have adopted the TIFF format for storage of the digitized images of their bank checks. In addition, some of these banking systems store four images of each check within the TIFF file. A first image corresponds to the front of the check, and a second image corresponds to the back of the check, as it initially arrives for processing. Later, during the check-clearing process, additional information can be added to the check, such as routing information. Two additional images, front and back, are created of the modified check, thereby explaining the total of four images.
The TIFF convention, or standard, allows these multiple digital images to be stored in a single data file. The use of a single file, as opposed to four separate files, provides convenience of handling, since only a single file must be named and tracked, as opposed to four files.
The Inventors have identified potential problems in this single-file approach to storage of multiple images, and have developed stratagems which reduces the problems.